Human leg

Your legs help you move.

They help you stand up tall. They also help you dance. We use them to walk every day.

Each leg has thirty bones. The big bone in your thigh is very long. Your leg has a part called the shin. The back of your lower leg is the calf. These strong legs help you walk on two feet. They are very good at supporting your body.

Your legs help you move and stand tall.

They are built for walking on two feet. This way of moving is called bipedalism. Humans have legs that are very long and strong. This helps us move with very little effort.

Each leg has thirty bones. The femur is the big bone in your thigh. The tibia is your shinbone. The fibula is a smaller bone next to it. Your kneecap is called the patella. It is the largest sesamoid bone in your body.

Many muscles help your legs work. The gluteus maximus is a large muscle in your hip. It helps you climb stairs or stand up. Other muscles help you move your legs in different ways. Some muscles pull your legs in. Others move them out to the side. These muscles also help you keep your balance.

Your legs are a big part of your body. They help you dance and play every day.

Your legs are amazing tools for moving through the world.

They allow you to stand up, walk, and even dance. Because they are so important, legs make up a large part of a person's total weight. In humans, the legs are specially made for walking on two feet. This way of moving is called bipedalism. While other primates can walk on two feet, they use a lot of energy to do it. Humans have evolved to make this movement very efficient and easy.

Each leg is built with a clever system of bones and muscles.

There are thirty bones in every single leg. The femur, or thigh bone, is the longest one. Below the knee, the tibia is your shinbone. The fibula is a smaller bone that sits right next to the tibia. Your kneecap is called the patella, which is a sesamoid bone. This is the largest sesamoid bone in your whole body.

These bones work together to support your weight as you move.

Muscles act like the engines that pull your bones into motion.

Many different muscles help you move your legs in many ways. For example, the gluteus maximus is a large muscle in your hip. It helps you do hard jobs like climbing stairs or standing up from a chair. Other muscles help you move your legs out to the side, which is called abduction. Some muscles pull your legs toward the middle of your body, which is called adduction. These muscles also help you keep your balance while you walk.

Scientists have studied how these parts line up perfectly.

Most of the large joints in your leg sit in a straight line. This line is called the Mikulicz line. It stretches from your hip, through your knee, and down to your ankle. There is also a special angle where your thigh bone meets your knee. This is called the femorotibial angle, and it is usually 174 degrees. If this angle changes, it can change how weight sits on your joints. Having the right angles helps your legs stay strong and healthy.

It is interesting to see how human legs differ from other animals.

Human legs are much longer compared to our trunks than other primates. For instance, a chimpanzee's leg is 128% of its trunk length. In humans, the leg is 171% of the trunk length. This huge difference is what makes us such good walkers. Our bodies even changed other things to help us stand tall. Our spine has an S-shape to act like a shock-absorber for our weight. This helps shift your weight safely onto your feet.

The human leg is a complex lower limb designed for support and movement. It includes the thigh, the knee, the lower leg, the ankle, and the foot. Some definitions even include the hip or buttock regions. Each leg contains thirty distinct bones. These bones form a structural framework that supports a significant portion of a person's total body mass. The leg is essential for standing, walking, and many forms of recreation like dancing.

To understand how the leg works, we must look at its skeletal structure. The thigh is the section between the hip and the knee. The lower leg, also called the crus or shank, lies between the knee and the ankle. In the front of the lower leg, the tibia, or shinbone, and the smaller fibula form the shin. The back of the lower leg is known as the calf. The femur, or thigh bone, is the major long bone of the upper leg. The patella, which is the kneecap, is a sesamoid bone. It is the largest sesamoid bone in the human body.

Human legs are uniquely specialized for an efficient bipedal gait, which means walking on two feet. Evolution has shaped our limbs to make this movement easy. While other primates can walk upright, they do so with a high expenditure of energy. In humans, the leg length is 171% of the trunk length. This is much higher than in chimpanzees, where it is 128%. In orangutans, the leg length is 111% of the trunk. This specialization has changed our entire body structure. Our spine has a double S-shape to act as a shock-absorber. This shape shifts weight from the trunk to the feet.

Anatomists use specific lines to describe the mechanical alignment of the leg. The Mikulicz line is a mechanical longitudinal axis. It stretches from the head of the femur, through the knee, to the center of the ankle. In a normal leg, the femoral shaft and the tibial shaft align in a specific way. The femorotibial angle is usually 174 degrees. If the knee joint is lateral to the mechanical axis, it is called genu varum. If the knee is medial to the axis, it is called genu valgum. These deviations can cause unbalanced loads on the joints.

Muscles act as the engines that move these bones through various directions. Hip muscles are categorized by their location and their function. For example, the gluteus maximus is a powerful extensor and lateral rotator. It is vital when climbing stairs or rising from a sitting position. Other muscles, like the gluteus medius and minimus, assist with abduction. Abduction means moving the leg away from the body's midline. Conversely, adduction involves pulling the leg toward the midline. Muscles like the adductor magnus and gracilis perform these tasks.

Specific muscle groups also control rotation and flexion. The iliopsoas is a group of muscles that helps with flexion, or bending the hip. It consists of the psoas major and the iliacus. The psoas major starts at the lumbar spine and stretches into the pelvis. The tensor fasciae latae is another important muscle for the hip. It helps the hip joint flex, rotate medially, and abduct. Some muscles, like the gracilis, are unique because they act on two joints. The gracilis reaches past the knee to attach to the tibia.

There are also measurable differences between biological sexes in leg structure. Female legs generally show greater hip anteversion and tibiofemoral angles. In contrast, male legs often have longer femur and tibial lengths. The angle of the femur, called the collodiaphysial angle, also changes with age. It is about 150 degrees in a newborn. It decreases to between 126 and 128 degrees in adults. By old age, it may reach 120 degrees. These structural details ensure that the human body can maintain balance and mobility throughout life.